The present invention relates to a novel electronic contact member and Manufacture thereof, and a vacuum interrupter, a vacuum circuit breaker, a load-break switch or the like using thereof.
It is required that an electric contact member has, for example, a voltage-proof performance and a melt-resistance function. In order to satisfy the above-mentioned requirement it is effective that the texture of a material of the contact member is fine and homogeneous, and accordingly, as disclosed in JP-A-10-223075, an electron beam or a laser beam having a high energy is irradiated onto the outer surface of an electric contact so as to melt and quench the surface of the contact in order to micro-structure the texture of the electric contact. Further, JP-A-2000-235825 discloses a thermal spraying process for manufacturing an electric contact member with the use of a melting and quenching process.
In a method disclosed in the JP-A-10-223075 in which the outer surface of an electric contact is melted by an electron beam or a laser beam and is then quenched so as to have a microstructure, atmospheric control for producing various beams is required, and accordingly, an equipment such as a chamber container or the like is required. Further, since a base member for the electric contact is first produced, and is then surface-treated, two process steps are inevitably required, resulting in an increase in the manufacturing costs. Further, since the diameters of various beams have a limitation, a huge time is required for the surface treatment over a wide area, thus, the productivity cannot be so high.
In a manufacturing method as disclosed in the JP-A-2000-235825 utilizing thermal spraying, although the productivity is excellent, the structure of a thermally sprayed layer serving as an electric contact member is composed of flat particles having a relatively large particle size, and accordingly, its voltage-proof is insufficient in such a condition that the contact surface is directly used as it is after the thermal spraying. Thus, after the electric contact is incorporated in a vacuum interrupter, there is required such a conditioning treatment that electric discharge is made across a gap defined between electrodes so as to remove a low voltage-proof part, thereby it hinder cost reduction.